Comparative Analysis of Signet Ring and Non-Signet Ring Urachal Adenocarcinomas: A National Cancer Database Study.

INTRODUCTION

Primary urachal adenocarcinomas are rare and histologically diverse. Signet ring cell carcinoma (SRCC), a poorly cohesive and aggressive variant, is associated with poor prognosis compared to non-signet ring urachal adenocarcinoma (UA). This study aims to compare the clinicopathologic features, treatment patterns, and survival outcomes between SRCC and UA.

METHODS

We retrospectively analyzed data from the National Cancer Database (2004-2020), including patients aged ≥ 18 with SRCC or non-signet ring UA located at the bladder dome. Demographics, staging, treatment modalities, and overall survival (OS) were compared using chi-square tests and Kaplan-Meier analysis.

RESULTS

Among 550 patients, 60 had SRCC and 490 had non-signet ring UA. Baseline characteristics were comparable, though SRCC cases showed more frequent under-staging and treatment at community centers. Median OS was significantly shorter for SRCC (29.6 vs. 79.0 months, P < .001). Partial cystectomy conferred better survival than radical cystectomy in both groups. Chemotherapy did not improve outcomes in SRCC and was associated with worse survival in UA, likely due to selection bias.

CONCLUSION

SRCC of the urachus is a biologically distinct subtype with significantly worse outcomes than non-signet ring UA, regardless of surgical approach. Histology-specific strategies are needed to improve survival in this rare, aggressive cancer.